The heritable disorders of connective tissue, include the Ehlers-Danlos Syndrome (EDS), Osteogenesis Imperfecta (OI) and the Marfan Syndrome. These disorders have been proposed to have underlying defects in collagen metabolism, and in the past five years defects in collagen biosynthesis have been detected in three forms of EDS and one form of OI. Bone collagen from patients with OI has also been found to have an increased hydroxylysine content compared to skin from OI patients and from normal individuals. I propose to use cultured skin fibroblast from OI patients to attempt to define environmental factors which accentuate the difference in hydroxylysine content of collagen from OI fibroblasts and normal fibroblasts. Several different genetic types of collagen have been described. I have isolated an antigenically distinct type of collagen from placentas which seems to be localized to the fibroblast membrane by indirect immunofluorescence and complement mediated cytotoxicity. I propose to purify this collagen, characterize the chain composition and perform peptide mapping and define the biological properties of this collagen.